BIOS - Bioenergy
  YOUR PARTNER FOR ENERGY FROM BIOMASS AND ENERGY EFFICIENCY  
 

Plant monitoring

Overview

Plant monitoring is the detailed evaluation of the performance of overall plants as well as of single plant components. In biomass heating and biomass CHP plants as well as biogas plants monitoring represents an important basis for process optimisation, especially during the start up phase and the first year of operation but also as a basis for trouble shooting.

The main objectives are:

  • plausibility check of the plant internal measurement and analyses devices
    (e.g.: furnace temperature measurements, heat and electricity measurements, flue gas and gas analysers),
  • determination of the efficiencies of emission reduction measures
    (dust separation efficiency of cyclones, ESPs and baghouse filters; efficiency of primary and secondary measures for NOx, SOx and HCl-emission reduction, etc.),
  • the performance of detailed mass and energy balance calculations over single plant components as well as over the whole plant in order to determine their efficiencies,
  • the quick optimisation of plant settings especially in the first year after plant start up,
  • the identification of bottle necks and malfunctions e.g. increased leakage flows, increased deposit formation on the furnace walls and on boiler tubes, etc.,
  • the detailed evaluation of the plant performance in order to optimise the plant settings with the aim to achieve operation at high efficiencies and low electricity consumption as well as low operation costs.

Based on these evaluations suggestions for improvements are worked out and forwarded to the plant operator or plant manufacturer.

At BIOS plant monitoring is generally based on three different approaches:

  • long term monitoring of biomass heating plants, biomass CHP plants and biogas plants
  • dedicated test runs with accompanying plant monitoring at biomass heating plants, biomass CHP plants and biogas plants
  • CFD-aided simulation of furnaces and boilers based on the data gained from test runs as well as mass and energy balancing over the plant

Long term monitoring of biomass heating plants, biomass CHP plants and biogas plants

The respective plant operation data needed for the monitoring are stored by the plants process control system over a certain period (some days or weeks) and then forwarded to BIOS, where they are evaluated by using especially in-house developed data evaluation software programs (DATEVAL).

References:

Dedicated test runs with accompanying plant monitoring at biomass heating plants, biomass CHP plants and biogas plants

Within dedicated test runs which usually last for several days, plant operation data are collected by the process control system and additionally, samples from all relevant in-going and out-going streams are taken. Moreover, relevant parameters are determined by BIOS engineers separately with mobile measurement device. Examples therefore are:

  • Flue gas composition
  • Temperatures and volume flows of the flue gas in different plant sections
  • Furnace and boiler temperatures
  • Deposit formation in furnaces and boilers (applying deposit probes)
  • Particle size distribution and concentration of fly ashes and aerosols (fine particulates) in different sections of the plant
  • Fuel and ash sampling and subsequent chemical analyses of the samples taken
  • Substrates and digestate sampling and subsequent analyses of the samples taken
  • Detailed analyses of the biogas produced

more...

Based on these measurement and analyses data as well as on mass and element balances calculated over single plant components respectively the whole plant the plant performance is evaluated.

References

CFD-aided simulation of furnaces and boilers based on the data gained from test runs as well as mass and energy balancing over the plant

CFD simulations allow for the spatially resolved calculation and visualisation of the turbulent reacting flow in biomass furnaces and boilers. An improved understanding of the fundamental physical and chemical processes as well as of the distributions of temperatures, flows and concentrations of gas phase compounds can thereby be gained.

CFD-Simulations

CFD-aided plant monitoring of plants is of great advantage, since it is based on real operation data and therefore allows for a detailed weak-point and error analysis. As an example, hot-spots causing slagging as well as reasons for too high CO emissions like a poorly stirred unburned flue gas or too short residence times at sufficient reaction temperatures can be identified. Consequently, CFD-aided monitoring provides for an efficient evaluation and optimisation of the plant operation.

Aims of CFD-aided plant monitoring

  • Validation of models / check of simulation results from preceding design studies
  • Determination of the effective heat transfer coefficient of refractory linings under consideration of ash deposit layers on furnace and boiler walls
  • Calibration of thermo couples by means of combined suction pyrometer measurements / CFD simulations as a basis for an improved temperature control in the combustion plant
  • CFD analysis of plant operation as a basis for an improved control concept and an operation optimisation
  • Error and weak-point analysis of furnace and boiler geometry as a basis for retrofitting measures for furnaces and boilers

The following improvements concerning plant operation can be achieved with theses measures (see also CFD simulations)

  • Reduction of CO and NOx emissions – identification of strain formation and weakly stirred flue gas flows
  • Compliance of a low air excess (high boiler efficiency)
  • Reduction of hard ash deposit formation – identification and avoidance of local temperature peaks
  • Reduction of erosion and material stress – identification and avoidance of velocity and temperature peaks
  • High plant availabilities

References